Laverne Cox distinctly remembers the first time she played with nail polish. It was a pretty pink color, and she was 6 years old. The actress and transgender activist grew up watching (and then, later, helping) her mother with the task before setting out to paint her own — and, if you've seen her talons as of late, you know she still hasn't slowed down.

The only difference now: Cox doesn't fuck around with pink anymore. These days, she prefers her nails sparkly, metallic, or red — and...